/Engine/Plugins/Online/OnlineFramework/Source/Party/Public/User/ISocialUserList.h
OSS-agnostic user state filters (presence info generally required). Some of these do imply others and some conflict. Up to consumers to responsibly choose appropriate combinations.
enum ESocialUserStateFlags { None = 0, Online = 1, Joinable = 1 << 1, LookingForGroup = 1 << 2, SamePlatform = 1 << 3, InGame = 1 << 4, SameApp = 1 << 5, SameParty = 1 << 6, }